A computer network is a collection of interconnected computing devices that can exchange data and share resources. Example computing devices include routers, switches, and other layer two (L2) network devices that operate within layer two of the Open Systems Interconnection (OSI) reference model, i.e., the data link layer, and layer three (L3) network devices that operate within layer three of the OSI reference model, i.e., the network layer. Network devices within computer networks often include a control unit that provides control plane functionality for the network device and forwarding components for routing or switching data units.
An Ethernet Virtual Private Network (EVPN) may be used to extend two or more remote L2 customer networks through an intermediate L3 network (e.g., a provider network), in a transparent manner, i.e., as if the intermediate L3 network does not exist. In particular, the EVPN transports L2 communications, such as Ethernet packets or “frames,” between customer networks via the intermediate L3 network. In a typical configuration, provider edge (PE) network devices (e.g., routers and/or switches) of the provider network coupled to customer edge (CE) network devices of the customer networks define label switched paths (LSPs) within the provider network to carry encapsulated L2 communications as if these customer networks were directly attached to the same local area network (LAN). In some configurations, the PE network devices may also be connected by Internet Protocol (IP) infrastructure in which case IP/Generic Routing Encapsulation (GRE) tunneling or other IP tunneling can be used between the PE network devices.